With the advent of the recent information society, the amount of information processed in an electronic device such as a personal computer is surprisingly increased with the significant increase of power consumption of the electronic device. Especially, in the portable electronic devices, a problem regarding the increase of the power consumption accompanied with the increase of processing capacity arises. While a lithium ion secondary battery is generally used as a power source in these portable electronic devices at present, the energy density of the lithium ion secondary battery approaches to its limit.
In order to extend a continuously usable period of the portable electronic devices, the reduction of the power consumption is required by suppressing the drive frequency of CPU.
Under the above circumstance, the significant extension of the continuously usable period of the portable electronic devices is expected by using a fuel cell having a larger energy density in place of the lithium secondary battery as their power sources.
A fuel cell configured by a fuel electrode and an oxidant electrode sandwiching an electrolyte generates power in accordance with an electrochemical reaction while fuel is supplied to the fuel electrode and an oxidant is supplied to the oxidant electrode. While hydrogen is generally used as the fuel, an improved fuel cell in which methanol usable as an inexpensive and easy-handling raw material is modified to generate hydrogen, and a direct-type fuel cell directly using the methanol as the fuel are extensively developed in the recent years.
The reaction on the fuel electrode in which the hydrogen is used as the fuel proceeds in accordance with a formula (1).3H2→6H++6e−  (1)
The reaction on the fuel electrode in which the methanol is used as the fuel proceeds in accordance with a formula (2).CH3OH+H2O→6H++CO2+6e−  (2)
In either case, the reaction on the oxidant electrode proceeds in accordance with a formula (3). 3/2O2+6H++6e−→3H2O  (3)
The fuel cell is classified into many kinds, and is broadly divided into an alkali type, a solid polymer type, a phosphoric acid type, a melt carbonate type and a solid electrolyte type.
JP-A-6(1994)-52878 discloses a phosphoric acid type fuel cell accommodated in a sealed vessel in which hydrogen acting as fuel is reacted with oxygen in air to generate power. In the sealed vessel, the oxygen in air is taken in and the reacted gas is discharged from the vessel during the operation of the fuel cell. An absorbent reproducible by heating is disposed in the sealed vessel. The phosphoric acid type fuel cell described in the publication solves a problem that generated moisture dropping in the sealed vessel reduces the phosphoric acid concentration to deteriorate the cell characteristics.